CN102017171A - Substrates for photovoltaics - Google Patents

Abstract

Light scattering substrates, superstrates, and/or layers for photovoltaic cells are described herein. Such structures can be used for volumetric scattering in thin film photovoltaic cells.

Description

Substrates for photovoltaic devices

This application claims priority to US Patent Provisional Application No. 61/039,398, filed March 25, 2008.

Background technique

field of invention

Embodiments relate generally to photovoltaic cells, and more particularly to light scattering substrates and superstrates for photovoltaic cells.

Background technique

For thin film silicon photovoltaic solar cells, light is preferably efficiently incorporated into the silicon layer, where it is then trapped, providing sufficient path length for light absorption. Particular preference is given to optical path lengths which are greater than the thickness of the silicon.

Conventional tandem cells combining amorphous silicon and microcrystalline silicon typically include: a substrate on which a transparent electrode is disposed, a top cell of amorphous silicon, a bottom cell of microcrystalline silicon, and a back contact or counter electrode. Light is typically incident from the side of the deposition substrate such that the substrate acts as a superstrate in this cell structure.

Amorphous silicon absorbs mainly in the visible part of the spectrum below 700 nanometers (nm), while microcrystalline silicon absorbs similarly to bulk crystalline silicon, with a gradual decrease in absorbance as it extends to about 1200 nm. Both materials can benefit from surfaces with increased scattering and/or improved transmission.

The transparent electrode (also known as transparent conducting oxide, TCO) is usually a fluorine-doped _SnO2 film (FTO) or an aluminum-doped or boron-doped ZnO (AZO or BZO, respectively) film with a thickness of about 1 μm , which are textured to scatter light into amorphous Si and microcrystalline Si. The primary measure of scattering is called "haze" and is defined as the ratio of the light scattered beyond 2.5 degrees of the beam entering the cell to the total light transmitted forward through the cell. Due to the wavelength dependence of the scattering surface, the haze is generally not a constant value over the broad solar spectrum from 300-1200 nm. In addition, as noted above, for light absorbed by a single pass through a uniform thin layer of silicon, the trapping of long wavelength light is more important than the trapping of short wavelength light.

In some conventional photovoltaic applications, the haze is about 10-15%, measured at a wavelength of 550 nm. However, the distribution function is not governed by this one parameter alone, large angle scattering is more effective at increasing path lengths in silicon than narrow angle scattering. The literature for different kinds of distribution functions shows that improved large-angle scattering has a significant impact on the performance of the cell.

TCO surfaces can be textured by various techniques. For example, for FTO, the texture can be controlled by the parameters of the chemical vapor deposition (CVD) method used to deposit the film. For AZO or BZO, plasma treatment or wet etching is usually used after deposition to form the desired morphology.

In the past, haze was usually written as a single number. The long wavelength response is particularly important for microcrystalline silicon. More recently, haze values as a function of wavelength have been reported. Because scattering is directly related to wavelength and the size of the scatterers, the wavelength response can be improved by changing the size of the features on the textured surface. Large and small feature sizes can be combined in a single texture while providing scattering at long and short wavelengths. Such structures also combine light-trapping functionality with improved light transmission. On the other hand, for amorphous Si, shorter wavelengths are beneficial.

Textured TCO technology may include one or more of the following disadvantages: 1) the rough structure of the texture can degrade the quality of the deposited silicon, causing electrical shorts, thereby reducing the overall performance of the solar cell; Optimization is limited by both the texture that can be formed by the deposition or etching process and the reduction in light transmission associated with thicker TCO layers; and 3) in the case of ZnO, the use of plasma treatment or wet etching to create the texture would increase cost.

Another approach to meeting the light-trapping needs of thin-film silicon solar cells is to texture the substrate beneath the silicon prior to deposition of silicon nitride, rather than texturing the deposited film. In some conventional thin film silicon solar cells, vias are used instead of TCOs to make contact with the bottom of the Si that contacts the substrate. The texturing in some conventional thin-film silicon solar cells consists of _SiO2 particles deposited in a binder matrix on a planar glass substrate. Such texturing is typically accomplished using a sol-gel process, in which particles are suspended in a liquid, the substrate is pulled through the liquid, and then sintered. The beads remain spherical, held in place by the sintered gel.

Textured glass substrate methods may include one or more of the following disadvantages: 1) sol-gel chemistry and related processes are required to provide bonding of the glass microspheres to the substrate; 3) additional costs associated with silica microspheres and sol-gel materials; and 4) problems with film adhesion and/or crack formation in silicon films.

Many additional methods have been developed to produce textured surfaces prior to TCO deposition. These methods include sandblasting, polystyrene microsphere deposition and etching, and chemical etching. These methods involving textured surfaces may be limited in the kinds of surface textures that can be formed.

类产品。通常采用辊压法形成该大规模结构。Light trapping is also advantageous for bulk crystalline Si solar cells where the Si thickness is less than about 100 microns. Below this thickness, there is not enough thickness to efficiently absorb all of the solar radiation in a single pass or in two passes (with reflective back contacts). Therefore, cover glasses with large-scale geometries have been developed to enhance light trapping. For example, an EVA (ethyl-vinyl acetate) encapsulant is provided between the cover glass and the silicon. An example of these cover glasses is available from Saint-Gobain Glass (Saint-Gobain Glass)

class products. The large-scale structure is usually formed using a rolling method.

It is preferred to use a substrate having light scattering properties sufficient to provide light trapping, especially longer wavelength light trapping. In addition, it is preferred that the substrate is planar, for example to allow subsequent film deposition without causing deleterious electronic effects.

Contents of the invention

The substrates as described herein address one or more of the disadvantages of conventional substrates for photovoltaic applications described above.

One embodiment is a photovoltaic device comprising a substrate, a conductive material adjacent to the substrate, and an active photovoltaic medium adjacent to the conductive material, the substrate comprising an inorganic matrix, and A region having light-scattering properties disposed in the inorganic matrix.

Another embodiment is a photovoltaic device comprising a substrate, a layer, a conductive material, and an active photovoltaic medium adjacent to the conductive material, the layer comprising an inorganic matrix and disposed on the A region in an inorganic matrix having light-scattering properties in which the layer is in physical contact with the substrate and in which the layer is disposed between the substrate and the conductive material.

Additional features and advantages of the present invention are set forth in the following detailed description, some of which are readily understood by those skilled in the art from the stated content, or through the illustrated description and its claims and appended It is recognized that the invention is practiced as described in the figures.

It is to be understood that both the foregoing general description and the following detailed description are examples of the invention, and are provided to provide a general overview or framework for understanding the nature and character of the invention.

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments of the invention, and together with the description serve to explain the principles and operations of the invention.

Description of drawings

The present invention can be better understood from the following detailed description when read in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram of features of a photovoltaic device according to one embodiment.

Figure 2 is a schematic diagram of features of a photovoltaic device according to one embodiment.

3 is a schematic diagram of features of a photovoltaic device according to one embodiment.

Figures 4a, 4b, 4c and 4d show scattering substrates according to some embodiments.

Figure 5 is a scanning electron micrograph (SEM) of exemplary particle shapes, distributions and sizes, according to some embodiments.

Figure 6 is a scanning electron micrograph (SEM) of exemplary particle shapes, distributions and sizes, according to some embodiments.

Figure 7 is a scanning electron micrograph (SEM) of exemplary particle shapes, distributions and sizes, according to some embodiments.

Figure 8 is a graph showing the air transmittance as a function of particle density for particles with a diameter of 500 nanometers.

Figure 9 is a plot of the integrand (Si absorbance, product of solar spectrum and wavelength) versus wavelength for particles with a diameter of 500 nm.

Figure 10 is a graph of the optimized particle density, transmittance-reflectance for 5e6.

Figure 11 is a plot of the corresponding angular intensity for an optimized particle density of 5e6.

Figure 12 is a graph of transmittance versus wavelength for a substrate obtained using photosensitive glass, according to one embodiment.

Figure 13 is a graph of the angular strength of a Fota-Lite ^™ substrate according to one embodiment.

Figure 14 is a graph of total transmittance versus wavelength, according to one embodiment.

Figure 15 is a graph of diffuse transmittance versus wavelength, according to one embodiment.

Figure 16 is a graph of the angular intensity of a layer according to one embodiment.

Detailed description of the invention

Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

In this context, the term "volume scattering" can be defined as the effect on the optical path caused by the non-uniformity of the refractive index of the material through which light passes.

In this paper, the term "surface scattering" can be defined as the effect of the roughness of the interface between layers in a photovoltaic cell on the light path.

Herein, the term "substrate" may be used to describe either the substrate or the superstrate, depending on the structure of the photovoltaic cell. For example, the substrate is a superstrate if the substrate is located on the light incident side of the photovoltaic cell when assembled into the photovoltaic cell. The covering can provide protection for the photovoltaic material from impact and environmental degradation while allowing transmission of suitable wavelengths in the solar spectrum. In addition, a plurality of photovoltaic cells can be arranged into a photovoltaic module.

As used herein, the term "adjacent" may be defined as immediately adjacent. Adjacent structures may or may not be in physical contact with each other. Adjacent structures may include other layers and/or structures disposed therebetween.

As used herein, the term "planar" may be defined as having a surface that is substantially flat in shape.

As shown in FIG. 1, one embodiment is a photovoltaic device 100 comprising a substrate 10, a conductive material 12 adjacent to the substrate, and an active photovoltaic medium 14 adjacent to the conductive material. , the substrate comprises an inorganic matrix 18, and a region 20 with light scattering properties disposed in the inorganic matrix.

In one embodiment, as also shown in FIG. 1 , the photovoltaic device 100 further includes a counter electrode 16, the counter electrode is in physical contact with the active photovoltaic medium 14, and the counter electrode is disposed on the On the opposite surface 22 of the active photovoltaic medium 14 is the conductive material 12 .

According to one embodiment, the active photovoltaic medium is in physical contact with the electrically conductive material. According to one embodiment, the conductive material is a transparent conductive film, such as a transparent conductive oxide. The transparent conductive film may include a textured surface.

According to one embodiment, said regions comprise one or more of the following: particles, bodies, spheres, precipitates, crystals, dendrites, phase-separated elements, phase-separated compounds, air bubbles, air lines, cavities or their The combination. Or for example the region may comprise particles, groups, spheres, precipitates, crystals, dendrites, phase-separated elements, phase-separated compounds, air bubbles , a variety of air lines, a variety of cavities, or a combination thereof.

In one embodiment, the matrix comprises a material selected from the group consisting of glass, glass-ceramic, and combinations thereof. In one embodiment, the region comprises a material selected from the group consisting of glass, glass ceramics, ceramics, metal oxides, metals oxides, and combinations thereof.

As shown in one embodiment of FIG. 2 , the photovoltaic device 200 further includes a layer 24, the layer 24 includes an inorganic matrix 28 and a region 26 with light scattering properties disposed in the inorganic matrix, the The layer is in physical contact with the substrate 10 , disposed between said substrate 10 and the conductive material 12 .

According to some embodiments, the layer has a thickness equal to or less than 1 mm, such as equal to or less than 800 microns, such as equal to or less than 500 microns, such as equal to or less than 250 microns, such as equal to or less than 100 microns, such as equal to or less than 50 microns , such as equal to or less than 25 microns, such as equal to or less than 15 microns, such as equal to or less than 10 microns. According to another embodiment, said layer has a thickness equal to or greater than 1 micrometer, for example 1-10 micrometers.

In some embodiments, the active photovoltaic medium includes multiple layers. For example, the plurality of layers may comprise one or more p-n junctions, such as in a Si cell. In one embodiment, the active photovoltaic medium comprises a tandem junction, CdTe, or (di)copper indium gallium selenide (CIGS).

Another embodiment shown in FIG. 3 is a photovoltaic device 300 comprising a substrate 30, a layer 32, a conductive material 12, and an active photovoltaic medium 14 adjacent to the conductive material, The layer 32 comprises an inorganic matrix 28 and a region 26 having light scattering properties arranged in the inorganic matrix, in the conductive material 12, the layer is in physical contact with the substrate 30, the layer is arranged in between the substrate and the conductive material.

According to some embodiments, the layer has a thickness equal to or less than 1 mm, such as equal to or less than 800 microns, such as equal to or less than 500 microns, such as equal to or less than 250 microns, such as equal to or less than 100 microns, such as equal to or less than 50 microns , such as equal to or less than 25 microns, such as equal to or less than 15 microns, such as equal to or less than 10 microns. According to another embodiment, said layer has a thickness equal to or greater than 1 micrometer, for example 1-10 micrometers.

In one embodiment, as also shown in FIG. 3 , the photovoltaic device 300 further includes a counter electrode 16, the counter electrode is in physical contact with the active photovoltaic medium 14, and is located on the active photovoltaic medium 14. 14 on the opposite surface 22, as the conductive material 12.

In the embodiment shown in FIG. 3, the substrate may or may not have volume scattering properties. According to one embodiment, the substrate is transparent. According to one embodiment, the substrate comprises a material selected from the group consisting of glass, glass ceramics and combinations thereof.

As noted above, conventional silicon photovoltaic cells use a structured surface as a means of reorienting light within the silicon layer and increasing the optical path length. An alternative approach is to use volumetric scattering within a planar substrate. These materials have been used in light scattering applications. Common examples include opal glasses and glass ceramics.

In one embodiment, the substrate comprises a plurality of domains dispersed throughout the volume of the inorganic matrix. In another embodiment, the substrate comprises a plurality of domains dispersed within a portion of the volume of the inorganic matrix. A further advantage can be obtained here of patterning the scattering regions within the substrate while maintaining a planar surface for subsequent deposition, eg deposition of TCO.

In some embodiments, the substrate includes regions arranged in a gradient in the following manner: from top to bottom in thickness, from left to right in thickness, from top to bottom over a portion of thickness, in thickness Part of the left to right, or a combination of these cases. Regions arranged in one or more patterns may also include the gradients described above within the one or more patterns. Exemplary embodiments of substrates 10 comprising regions are shown in Figures 4a, 4b, 4c and 4d. According to some embodiments, the matrix material, domain structure, domain material and domain arrangement may be the same as described above.

A substrate or layer with patterned regions can provide light trapping in the non-scattering portion of the substrate while providing light trapping in the Si. In various embodiments, the scattering layer can be formed by lamination, lamination fusion, thin film deposition, or photo-induced crystallization (eg, Fota-Lite ^™ ). In one embodiment, the scattering layer or film can be formed by embedding high (or low) refractive index microparticles or microspheres in a thin planarized layer. In one embodiment, the bulk or thin layer volume scattering material is a phase separated glass or glass ceramic.

There are a wide variety of materials suitable for use as volume scattering substrates and/or layers. Suitable materials include glass ceramics including, but not limited to, e.g., mullite, beta-quartz, willemite, wollastonite, and Dicor ^™ ; phase-separated glasses (e.g., opal) including, but not limited to, e.g., barium opal, silica barium acid opal, fluoride opal, and lead silicate opal; photosensitive glasses, including but not limited to, for example, Fotalite ^™ and FotaForm ^™ (available from Corning Incorporated); and photorefractive materials (including glass, glass-ceramic, and crystal).

Among the various materials, the scattering particles can be formed in situ from a homogeneous material, or added to make a composite mixture. The material can be melted using suitable processing techniques, including thermal processing techniques (eg, heating), chemical processing techniques (eg, ion exchange), and/or photosensitive techniques (eg, UV, ultraviolet, and/or laser irradiation). In some embodiments, volume scattering structures are formed by techniques such as photolithography, which allow the material to be physically oriented (e.g., mechanically, such as by stretching, or thermally, by applying a thermal gradient across the substrate), or by Ion exchange is performed on the surface layer. In one embodiment, the processing technique is such that the substrate material phase separates. In one embodiment, the processing technique results in precipitation in the substrate. In one embodiment, the processing technique results in the formation of a two-phase media.

In photosensitive glasses, such as FotaLite ^(TM) , the depth and pattern of one or more volumetric scattering regions can be controlled by controlling the time, area and intensity of exposure.

A wide variety of materials can be used depending on the desired properties of the substrate such as scattering angle, transmittance and wavelength dependence. In PV applications, desired properties typically include wide-angle scattering, high transmittance, and wavelength-independent properties. The various properties can be affected by the size, shape and distribution of the scattering particles. Exemplary particle shapes and sizes are shown in Figures 5, 6 and 7, showing glass-ceramic, mullite and Fota-Lite ^™ , respectively. These materials may be used as a substrate, or may be used as a layer, or may be used for one or both of the substrate and the layer.

In one embodiment, volumetric scattering within the substrate is combined with scattering from a rough surface (e.g., for a roughened TCO) to achieve overall optimized performance without using an overly rough surface that degrades the PV cell. performance. In one embodiment, a rough TCO is provided to reduce Fresnel reflections expected from planar materials with different refractive indices (TCO~2.0, Si~4).

In the case of thin (<~100 microns), bulk Si, EVA is used instead of TCO, while Si is much thicker. As in the case of thin-film Si, there is a trade-off between transmittance and scattering required for light trapping. In this case, high transmission in the visible wavelength range appears to be more critical, since below these thicknesses light trapping is only required at the longest wavelengths absorbed by Si.

According to one embodiment, the substrate is flat. In one embodiment, the layer is flat. According to another embodiment, the substrate and layer combination is planar. One advantage of using volume scattering flat substrates for light scattering is that electrical and crystal growth defects of structured substrates can be overcome. By improving the quality of silicon, it can lead directly to improved performance of solar cells. For thin-film technologies requiring transparent conductive electrodes, TCOs do not need to have a dual-mode texture and thus can be deposited cost-effectively using in-line and continuous CVD systems. Additionally, the thickness of the active Si film can be fine-tuned and reduced to minimize module deposition costs.

For thin-film technologies that do not require transparent conductive electrodes, the light confinement system is directly integrated within the glass substrate, thereby minimizing the number of module fabrication steps and obtaining a sustainable cost-saving solution. For thin monolithic Si solar cells, planar scattering substrates offer the advantage of being able to provide light trapping without texture on top of the superstrate, which would be exposed to the environment and prone to fouling. Depending on the method chosen to make the scattering substrate, some embodiments also provide the advantage that subsequent processing steps are not required after the substrate is formed (eg, in one embodiment, a fusion-formable opal glass substrate). The fabrication methods described below are suitable for very large fusion formable substrates such as those currently produced by Corning Incorporated for display applications.

Volume scattering substrates can provide highly dispersed light distribution. For thin film photovoltaic (PV) applications, embodiments of the volume scattering substrate may also provide sufficient transmission to absorb incident light. This suggests that there may be an optimal amount of scattering that can compete with light transmission and light trapping.

To evaluate the performance of substrates with dispersed volume scattering, a simplified cell configuration model was constructed consisting only of the substrate and 1 μm of Si on top of the substrate. In addition, the backside of the Si is modeled as a 100% reflective backside in the area where the backside contact is made. The thickness of the glass substrate is 0.7 mm. The model ignores the effect of TCO. Scattering particles are defined as having a diameter of 50-2000 nanometers and a refractive index of 2.1 or 1.8 within a glass with a refractive index of 1.51. For various particle sizes, the density was varied to maximize the maximum achievable current density (MACD). MACD is defined by Equation I below:

$\mathrm{<span\; class="notranslate">\; MACD</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; q</span>}}{\mathrm{<span\; class="notranslate">\; hc</span>}}<span\; class="notranslate">\; \&Integral;</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; AM</span>}\mathrm{<span\; class="notranslate">\; 1.5</span>}\mathrm{<span\; class="notranslate">\; G</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&lambda;d\&lambda;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; I</span>}$

Where q is the element charge, h is Planck's constant, c is the speed of light in vacuum, A is the absorbance in Si as a function of wavelength, I _AM1.5G is the solar spectrum, and λ is the wavelength. Integration was performed from 300 nm to 1200 nm. Using MACD, it is assumed that every photon absorbed by Si is converted into an electron. This is obviously an ideal situation, ignoring the electrical properties of materials and devices. However, it does characterize the light concentrating efficacy of the device structure. The model was built using Optical Research Associates' LightTools, followed by calculations of Si absorbance and MACD outside of LightTools.

For particles satisfying n=2.1, where n is the refractive index of the particle, Table 1 shows the optimized values. Particle size is the diameter of the particle.

Table 1.

For the n=1.8 particles, it was found that a similar percentage improvement was obtained.

Small variations in the MACD of particles of 200nm, 500nm and 2000nm can be within the error of the simulation. The refractive index of the particles does not significantly affect the results, but does change the optimal particle density. The table also shows the percent improvement over the substrate not including scattering. These are preliminary results, showing that it is possible to obtain significant improvements over flat, non-scattering substrates.

Figure 8 provides an example of obtaining the best PV cell performance (determined by MACD) by optimizing particle density using particles of 500 nm in size with n=2.1 in a material with n=1.51, where n is the refractive index. The particle density is 1e6 to 1e7 1/mm ³ . For a 1 micron layer of crystalline silicon, the optimum particle density is 5e6 1/mm ³ . The integrand used to calculate the MACD was plotted against three different particle densities. The curves show low values, especially for low particle densities at longer wavelengths; high values for all wavelengths for optimal particle densities, and low values at short wavelengths for high particle densities, at Long wavelengths show high values. Line 34 shows the transmission versus wavelength for a particle density (1/mm ³ ) of 1e6. Line 36 shows the transmission versus wavelength for a particle density (1/mm ³ ) of 5e6. Line 38 shows the transmission versus wavelength for a particle density (1/mm ³ ) of 1e7.

The glass incorporating these particle densities was simulated as a slab in air to evaluate its transmittance, reflectivity, and scattering properties. Figure 9 shows the total transmittance as a function of particle density. It is expected that as the particle density increases, the overall transmission through the thick plate decreases. This results in a shift in the wavelength-dependent properties of the integrand described above. The reduction in transmittance in the longer wavelength range redirects light reflected from the glass/Si interface towards Si, thereby increasing the Si absorbance at longer wavelengths. The decrease in transmission at shorter wavelengths offsets this benefit, so there is an optimum in absorbance where the two effects are balanced. Line 44 shows the integrand-wavelength plot for a particle density (1/mm ³ ) of 1e6. Line 40 shows the integrand versus wavelength for a particle density (1/mm ³ ) of 5e6. Line 42 shows the integrand-wavelength plot for a particle density (1/mm ³ ) of 1e7.

For an optimized particle density of 5e6, the transmittance and reflectance are shown in Figure 10, where line 46 is the transmittance and line 48 is the reflectance. Figure 11 shows the corresponding angular intensity curves for the optimized particle density, showing a strong specular reflection peak with a broad angular scattering bottom part. Line 50 is transmitted scatter and line 52 is reflected scatter.

Figure 12 is a graph of transmittance versus wavelength for a substrate obtained using photosensitive glass, according to one embodiment. In this example, the photosensitive glass was Fota-Lite ^(TM) , 2 mm thick, exposed to 248 nm light at a dose of 10 mJ/pulse. Line 54 shows the total transmission of the glass exposed to 10 pulses. Line 54a shows the diffuse transmission of the glass exposed to 10 pulses. Line 55 shows the total transmission of the glass exposed to 12 pulses. Line 55a shows the diffuse transmission of the glass exposed to 12 pulses. Line 56 shows the total transmission of the glass exposed to 15 pulses. Line 56a shows the diffuse transmission of the glass exposed to 15 pulses.

Figure 13 is a graph of angular intensity cosine corrected bidirectional transmission function (ccBTDF) versus angle for Fota-Lite ^™ exposed to 12 pulses of light at wavelengths of 400nm, 600nm, 800nm and 1000nm. Figure 13 shows few or no specular peaks, with wide angle scatter.

14 is a plot of total transmission versus wavelength for a layer comprising a composite glass matrix comprising _Ti02 particles, according to one embodiment. Samples were prepared in which the layers contained 1%, 2.5%, 5% and 7.5% _TiO2 . Line 58, line 60, line 62 and line 64 show the total transmission of layers containing 1%, 2.5%, 5% and 7.5% _TiO2 , respectively.

15 is a graph of diffuse transmittance versus wavelength for a layer comprising a composite glass matrix comprising _Ti02 particles, according to one embodiment. Samples were prepared in which the layers contained 1%, 2.5%, 5% and 7.5% _TiO2 . Line 66, line 68, line 70 and line 72 show the diffuse transmission of layers containing 1%, 2.5%, 5% and 7.5% _TiO2 , respectively.

Figure 16 is a plot of angular intensity cosine corrected bidirectional transmission function (ccBTDF) versus angle for layers containing 1% _Ti02 for light at wavelengths of 450nm, 600nm, and 800nm.

Haze can be determined by calculating the ratio of diffuse transmittance-total transmittance.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (26)

1. Photovaltaic device, it comprises:

A kind of base material, it comprises inorganic matrix and is arranged on the zone with light scattering character in the described inorganic matrix;

Electric conducting material with base material adjacent; And

The active photovoltage medium adjacent with described electric conducting material.

2. device as claimed in claim 1 is characterized in that described electric conducting material is a nesa coating.

3. device as claimed in claim 2 is characterized in that described nesa coating has textured surface.

4. device as claimed in claim 3 is characterized in that, described active photovoltage medium contacts with described nesa coating physics.

5. device as claimed in claim 1 is characterized in that, described device also comprises electrode, described electrode is contacted with described active photovoltage medium physics, is arranged on the opposed surface of described active photovoltage medium, as electric conducting material.

6. device as claimed in claim 1, it is characterized in that described device also comprises a layer, described layer comprises inorganic matrix and is arranged on the zone with light scattering character in the described inorganic matrix, described layer contacts with described base material physics, between described base material and electric conducting material.

7. device as claimed in claim 1 is characterized in that, described base material comprises a large amount of zones that are dispersed in the whole volume of inorganic matrix.

8. device as claimed in claim 1 is characterized in that, described base material comprises a large amount of zones that are dispersed in the inorganic matrix part volume.

9. device as claimed in claim 1 is characterized in that, described matrix comprises and is selected from following material: glass, glass ceramics and their combination.

10. device as claimed in claim 1, it is characterized in that described zone comprises following one or more: particle, group, spheroid, sediment, crystal, dendritic crystal, the element that is separated, the compound that is separated, air bubble, air lines, hole or their combination.

11. device as claimed in claim 10 is characterized in that, described zone comprises and is selected from following material: glass, glass ceramics, pottery, metal oxide, mixed-metal oxides and their combination.

12. device as claimed in claim 1 is characterized in that, described active photovoltage medium comprises a plurality of layers.

13. device as claimed in claim 1 is characterized in that, described substrate is the plane.

14. a Photovaltaic device, it comprises:

Base material;

A layer, it comprises inorganic matrix and is arranged on the zone with light scattering character in the described inorganic matrix;

Electric conducting material:

Described layer contacts with described base material physics, between described base material and described electric conducting material;

The active photovoltage medium adjacent with described electric conducting material.

15. device as claimed in claim 14 is characterized in that, described electric conducting material is a nesa coating.

16. device as claimed in claim 15 is characterized in that, described nesa coating has textured surface.

17. device as claimed in claim 16 is characterized in that, described active photovoltage medium contacts with described nesa coating physics.

18. device as claimed in claim 14 is characterized in that, described device also comprises electrode, described electrode contacted with described active photovoltage medium physics, is arranged on the opposed surface of described active photovoltage medium, as electric conducting material.

19. device as claimed in claim 14 is characterized in that, described layer comprises a large amount of zones that are dispersed in the inorganic matrix volume.

20. device as claimed in claim 14 is characterized in that, described layer comprises a large amount of zones that are dispersed in the inorganic matrix part volume.

21. device as claimed in claim 14 is characterized in that, described matrix comprises and is selected from following material: glass, glass ceramics and their combination.

22. device as claimed in claim 14 is characterized in that, described zone comprises: particle, group, spheroid, sediment, crystal, dendritic crystal, the element that is separated, the compound that is separated, air bubble, air lines, hole or their combination.

23. device as claimed in claim 22 is characterized in that, described zone comprises and is selected from following material: glass, glass ceramics, pottery, metal oxide, mixed-metal oxides and their combination.

24. device as claimed in claim 14 is characterized in that, described active photovoltage medium comprises a plurality of layers.

25. device as claimed in claim 14 is characterized in that, described layer is the plane.

26. device as claimed in claim 14 is characterized in that, the combination of described base material and layer is the plane.

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